Decided to go ahead and try the .2mm (32AWG) wire after reading on the Geotec Forum someone used it with reasonable results.

DC Resistance goes up but it seems with little consequences. Here are some basic numbers but sense I'm going with a 1" or so smaller form I will need a few more wraps or turns of wire to meet the uH numbers.

Coil came out to 5.5mH prior to lashing and was able to get it spot on 6.5 by lashing it. It will change some with added pressures from spiral wrap I'm sure. I hit it with some krylon paint as adhesive to try and keep it from moving much.

I wrapped coil with the Teflon and things did change a bit but not as expected. The uH went down. LOL Now getting like 6.367. I'll play at wrapping some more Teflon tighter and see if I can get it back up. I'm good with that. I can make up the difference on Tx if needed and still be will in the 14Khz Tx.

Dave I will just tac glue them to some card board to get them Nulled. That requires moving one or both coils to the point that the Rx Coil is cancelling out the Transmitted signal. At this point the Receive signal will be based on mostly the Target Signal only.

Later I will glue the card board on some foam as filler/spacer. Later I'll blow expanding foam in the housing securing all. In this case the Shielding is going to be a Conductive Carbon based paint within the coil housing.

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Ahh...I see! So the initial tacking down is just for tuning the coils. How much leeway is there in the coils position to each other? If you bump one and move it a couple thousandths during assembly...will it screw up your tuning?

Piles of stuff can come to play. You want the two coils as symmetrical to each other as possible. Shift one or the other laterally can throw you out. Just a mm or so can mean in or out of what your looking for. When you get done it's best to have any output on the Rx Positive of the Null on this detector.

LOL, only a couple of hours. Not done fuddling with it yet. Think I can just change the Bias on the Transistor and get it to do it's thing. It starts some times and not others.

I used the new Printer to print a few (10) pages of that program I'm working on. Have one section all marked up as to what changes I need . Going to make those changes and give it a go. I need to bread board the Display to the MEGA2560 and see if it will run. Wish I knew what I was doing a whole lot better !